Medical Definition of Vasopressin

Vasopressin: A relatively small (peptide)
molecule that is released by the
pituitary gland at the base of the brain after being made
nearby (in the
hypothalamus). Vasopressin has an antidiuretic action that
prevents the
production of dilute urine (and so is antidiuretic). A
syndrome of
inappropriate secretion of vasopressin which results in the
inability to put
out dilute urine, perturbs fluid (and electrolyte) balance,
and causes
nausea,
vomiting, muscle cramps, confusion and convulsions may
occur in association
with oat-cell lung cancer, pancreatic cancer, prostate
cancer, and Hodgkin's
disease as well as a number of other disorders. Vasopressin
has a
vasopressor
action and so can stimulate contraction of arteries and
capillaries. Hence
the
name "vasopressin." Vasopressin is also known as
antidiuretic hormone
(ADH).